This invention relates to a data communication system capable of communicating with communications apparatus of a plurality of types.
In a system of this kind, a mixed mode terminal capable of handling e.g. character code data and image data is capable of communicating with a facsimile device, a telex device and a mixed mode terminal.
When such a mixed mode terminal transmits data, there are cases where data transmission cannot be achieved, depending upon the type of data and the terminal characteristics of the other party. For example, if an attempt is made to transmit image data to a teletex device, the data ordinarily cannot be transmitted. Accordingly, the operator must decide whether or not to instruct that the transmission be made upon taking into consideration whether or not the other party is capable of receiving the data to be transmitted.
Thus, unless the operator is aware of the other party's terminal characteristics and the mode of the data to be transmitted, the proper transmission instruction cannot be made. This means that the transmission system cannot be simply operated by an ordinary individual. Furthermore, if the instruction to transmit the data is inputted to the system in spite of the fact that the transmission actually is not possible, the equipment operates wastefully. Moreover, since the input of the instruction to send the data will be judged to be illegal on the side of the other party only after the input has been connected to the communication line of the other party's terminal, the sending party must bear the charge of using the communication line until the line is opened.